As a part of health care, measurement of pulse wave velocity and blood pressure is conducted. For example, when blood pressure is measured, a cuff is fitted around the arm of a subject, the artery is blocked by the arm being pressed with the cuff, and thereafter, blood pressure is measured by use of vibrations caused in the blood vessel wall as the cuff is depressurized.
However, the manometer has drawbacks that, for example, the many steps for measuring blood pressure are troublesome, the device itself is large and difficult to be always carried, and the measurement of blood pressure is burdensome since the arm is pressurized in the measurement.
Therefore, aiming to improve the user-friendliness, for example, a wrist watch type blood pressure measuring device has been proposed. In the wrist watch type blood pressure measuring device, the function of measuring blood pressure is incorporated into a wrist watch that is small sized and carried around on a daily basis. The wrist watch type blood pressure measuring device is fitted around the left wrist, and a finger tip of the right hand is placed on a front face portion where a phototransistor and an electrocardiographic wave detecting electrode, which is an electrode for detecting electrocardiographic waves, are provided side by side. The wrist watch type blood pressure measuring device detects electrocardiographic waves from the fingertip of the right hand placed on the electrocardiographic wave detecting electrode and the left wrist contacting the electrocardiographic wave detecting electrode, and detects finger pulse waves from blood flow in the fingertip of the right hand placed on the phototransistor. The wrist watch type blood pressure measuring device then measures a delay time from the detection of the electrocardiographic waves to the detection of the finger pulse waves, and calculates the blood pressure based on the delay time.
Patent Document 1: Japanese Laid-open Patent Publication No. 04-200439
Patent Document 2: Japanese Laid-open Patent Publication No. 2007-319246
However, by the above described techniques, blood pressure is unable to be measured without extra hardware.
For example, the wrist watch type blood pressure measuring device measures the delay time between the electrocardiographic waves and the finger pulse waves by using dedicated hardware, such as the electrocardiographic wave detecting electrode or the phototransistor, which is not installed in a general wrist watch. Therefore, by the wrist watch type blood pressure measuring device, without the installation of the dedicated hardware, the delay time is unable to be measured and blood pressure found from the delay time is also unable to be measured.
The measurement of blood pressure has been described above, but similarly, pulse wave velocity found from the delay time is also unable to be measured without dedicated hardware.